Rotating
flush bowl
Membranes
Output tanks
for liquid
Drying
chamber
Vent
Output tank
for solids
Liquids
warming coil
Clean water
Collection
tank
Holding
chamber
Clean-water
tank
Reactor
chamber
DECODER BY MANUEL CANALES
A GLOBAL PROBLEM
More than half the world’s people lack safe
sanitation. Almost a billion defecate out-
doors. Some 361,000 children under age
five die each year from sanitation-related
diseases. It’s an urgent issue in cities,
where two-thirds of us may live by 2050.
HTClean’s vacuum flush uses water reclaimed from the
toilet’s high-temperature and pressure-separation process.
The result is purified water and disposable solid-waste
cakes. The sewer-free commode currently relies on electric-
ity, but scientists are working to make it completely off-grid.
HIGH PRESSURE AND HEAT
A low-water flush is acti-
vated by touch screen.
Vacuum suction moves
the waste and water
into a collection tank.
Excess liquid is
moved to a tank
for disposal or
another use.
The waste is pre-
heated and moved
to a reactor where
pressure and more
heat turn it into
liquid and carbonic
material.
Multistage filters
purify the liquid into
water that is used
to flush the toilet.
A mechanical press
squeezes liquid out
of the material, leaving
cakes of waste that can
be safely discarded
and water that is then
sent through filters.
Normal use
yields about 30
10-gram waste
cakes a day.
PATRICIA HEALY. ART: BRUCE MORSER. SOURCES: BILL & MELINDA GATES FOUNDATION; ALISON PARKER,
CRANFIELD UNIVERSITY; CHRISTIAN SEILER, HELBLING; WHO/UNICEF JMP; UNESCO WWAP
THE PROCESS TAKES
ABOUT 3-4 HOURS
TO COMPLETE.
1
2
3
Total
population
Practice open
defecation
7.6 bil
892 mil
4.5 bil Lack safely managed
sanitation services
USERS
PER DAY
10 YEARS’
LIFE SPAN
ELECTRICITY
REQUIRED
20